54 Bibliographical Notices. 



subject of coal- resources, and has treated it very satisfactorily, bring- 

 ing to the task good geological knowledge and conscientious exacti- 

 tude. 



The second edition of this work has quickly followed on the first, 

 with additional information, partly derived from the experience of 

 others (chiefly colleagues in the Geological Survey), and partly 

 elaborated by the author. 



The probable duration of our coal-supply is, of course, a most in- 

 teresting point of inquiry, and has been the subject of innumerable 

 treatises and newspaper articles. Mr. Hull, on careful consideration 

 of known facts, states that possibly, if the increase of coal-consump- 

 tion continue to enlarge in future years in the same ratio that it has 

 of late progressed, our coal will barely last for 325 years ; but he 

 adds that various causes may interfere with this rapidly progressing 

 ratio, some, however, accelerating rather than diminishing it. 



To the naturalist a wide field of research is opened by the working 

 of the coal-measures and the associated strata. The fossils, as the 

 palseontologist knows, are numerous and highly interesting. Besides 

 the plants, some are terrestrial, and many are referable to genera 

 that now inhabit the sea ; others have apparently such close rela- 

 tionship to some existing fluviatile and estuarine animals that many 

 strata in the old Carboniferous Formation have been regarded as 

 having been formed in brackish, if not fresh, water. The wholly 

 marine condition, however, of the coal-beds is at present recognized 

 by several authoritative geologists ; and nowhere perhaps is this view 

 better supported than in H. I). Rogers's great work on the Geology 

 of Pennsylvania. Mr. Binney, too, and Mr. Salter have their own 

 facts and arguments in support of the theory that coal-jungles grew 

 in shallow seas. The combination, however, of sea, estuary, lagoon, 

 and river in the formation of coal, on an oscillating sea-board, is 

 succinctly stated in Mr. Hull's chapters (II. & III.) on theFormation 

 of Coal ; but the possibly freshwater or brackish character of some 

 of the Mollusks found in certain beds (Anthracomya, Anthracosia, 

 &c.) is perhaps allowed to lapse too readily. The presence of 

 Estheria (whose existing species have freshwater habitats) in the 

 Coal-formation, as lately announced in the 'Neues Jahrbuch,' 1861, 

 may also be found to influence opinions on this subject. 



The fossil flora of the Coal is still imperfectly known. Geinitz, of 

 Dresden, has produced a work on the Carboniferous plants of Saxony, 

 which may well serve as a model for British palseobotanists. Exact 

 observation on the relative distribution of the fossil plants and other 

 organisms, hitherto collected far too indiscriminately to serve the 

 purpose of exact geology, has already been insisted upon by Mr. 

 Salter and others. Many a good specimen of reptile, fish, crusta- 

 cean, mollusk, &c, has been stored, described, and figured, without 

 its position in the coal-measures having been noted with sufficient 

 exactness ; and it has therefore proved of about as much use to the 

 geologist as a medal of unknown origin could be to a numismatist. 



The physical structure of the Coal-fields is a life-study for any 

 geologist. The Geological Surveyors of Great Britain and Ireland 



